<!DOCTYPE html>

<head>
	<title></title>
	<style>
		.box {
			height: 400px;
			display: -webkit-box;
			-webkit-box-orient: vertical;
		}
		
		.box div {
			height: 100%;
		}
		
		.div1 {
			border: 1px solid red;
			-webkit-box-flex: 1;
		}
		
		.div2 {
			border: 1px solid red;
			-webkit-box-flex: 1;
		}
		
		.div3 {
			border: 1px solid red;
			/*background-color: green;*/
			-webkit-box-flex: 1;
		}
		
		.div4 {
			border: 1px solid red;
			/*background-color: darkblue;*/
			-webkit-box-flex: 1;
		}
	</style>
</head>

<body>
	<div class="box">
		<div class="div1">
		</div>

		<div class="div2">

		</div>

		<div class="div3">

		</div>

		<div class="div4">
		</div>
	</div>
</body>

</html>